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عنوان فارسی مقاله:
بررسی چند روش متاکائولین و سرباره مخلوط خمیر سیمان پرتلند
عنوان انگلیسی مقاله:
Multi-technique investigation of metakaolin and slag blended portland cement pastes
سال انتشار : 2016
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مقدمه انگلیسی مقاله:
1. Introduction
Metakaolin (MK) is a relatively new supplementary cementitious material (SCM) that has been introduced in the 1990s (Ramezanianpour, 2014). MK is a pozzolanic material obtained by subjecting kaolin to heat treatment (calcination) at 500–800 °C. Upon heating, kaolinite (SiO2·2Al2O3·2H2O) is dehydroxylated and transformed into a more disordered metakaolin phase (Shvarzman et al., 2003). MK generally consists of 50% SiO2 and 40% Al2O3, although its exact composition varies depending on the source of kaolin clay (Ramlochan et al., 2000; Kakali et al., 2001; Shvarzman et al., 2003; Bich et al., 2009). Incorporation of MK into concrete has been gaining popularity due to the increase in early compressive strength and reduced permeability (Gruber et al., 2001; Justice et al., 2005; Poon et al., 2006; Duan et al., 2013). MK is typically added to concrete at cement replacement level of 10% in order to maximize compressive strength (Ambroise et al., 1994; Poon et al., 2001; Batis et al., 2005). It has been established that maximum contribution of MK to compressive strength occurs at approximately 14 days, after which the pozzolanic reaction of MK slows down (Wild et al., 1996; Ramezanianpour, 2014). Therefore, early-age properties of the OPC/MK mixtures are of particular interest in studying the effect of MK. While the effect of metakaolin on hardened concrete properties has been the topic of a large number of studies, its effect on the paste microstructure has not been explored in as much detail. Incorporation of MK is known to alter the chemical composition of CSH (Ambroise et al., 1994; Richardson, 2004), which is the main hydration product and is primarily responsible for concrete compressive strength. This change in CSH composition implies a possible change in its microstructure and mechanical response. Recently, Rodriguez et al. (2015) demonstrated that the CSH morphology changes from fibrillar to foil-like as the Ca/Si ratio decreases from 1.63 to 1.33. Several molecular simulations showed a change in the mechanical properties of CSH with the change in Ca/Si ratio (Abdolhosseini Qomi et al., 2014; Bauchy et al., 2014; Hou et al., 2015). Nanoindentation has been extensively used to ascertain the mechanical properties of CSH, which is the main hydration product and is primarily responsible for concrete compressive strength. It has been established that the mechanical response of CSH depends on the packing density of CSH globules (Constantinides and Ulm, 2007; Ulm et al., 2007; Ulm et al., 2010; Ioannidou et al., 2016). Values of elastic moduli have been published for a number of CSH morphologies which are summarized in Table 1. There exists a very porous phase, the elastic modulus of which is affected by capillary porosity (Constantinides and Ulm, 2007; Mondal et al., 2010; Hu et al., 2014), with a modulus of approximately 8–13 GPa, low-density or outer product CSH with an elastic modulus ≈ 21 GPa, high-density or inner product CSH with a modulus ≈ 30 GPa, and CH or a mixture of CSH and CH also referred to as ultra-high-density CSH with a modulus of 36–40 GPa. While nanoindentation has been applied to C3S and OPC pastes, there are few studies on nanoindentation of OPC/MK samples. He et
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کلمات کلیدی:
Multi-technique investigation of metakaolin and slag blended portland ... https://www.deepdyve.com/.../multi-technique-investigation-of-metakaolin-and-slag-ble... Jul 22, 2016 - Read "Multi-technique investigation of metakaolin and slag blended portland cement pastes" on DeepDyve - Instant access to the journals you ... Physico-chemical Properties of the Hardened Blended Cement Pastes ... issres.net/jbsr/pubsystem/index.php/cam/article/view/40 by MR Shatat - 2016 - Cited by 1 - Related articles In blended cement, it was known that, metakaolin (MK) has a pozzolanic activity. ... on the properties of portland cement pastes containing metakaolin, Silicates ... in Slag Cement-CKD Pastes under Hydrothermal Treatment, Journal of Wuhan ... Waste Materials and By-Products in Concrete https://books.google.com/books?isbn=3540742948 Rafat Siddique - 2007 - Technology & Engineering ... that ultra-fine slag can improve the physical properties of MK blended cement: (iii) ... clinker hydration to produce secondary C-S-H gel inside the cement paste. ... times of Portland cement containing metakaolin (MK) and ultra-fine slag (S). Mineral Admixtures in Cement and Concrete https://books.google.com/books?isbn=1439817928 Jayant D. Bapat - 2012 - Technology & Engineering Wild S., Khatib I. M., Portlandite consumption in metakaolin cement pastes and mortars, ... improvement of Portland cement by incorporating with metakaolin and slag, Cem. ... S., Pera, I., Properties of metakaolin blended cements, Adv. Cem. Clay Materials Used in Construction - Page 434 - Google Books Result https://books.google.com/books?isbn=186239184X George M. Reeves, Ian Sims, J. C. Cripps - 2006 - Science Pozzolanas can be used in conjunction with Portland cement because calcium hydroxide ... up to 25% of the mass (and volume) of fully cured Portland cement paste. ... and ground granulated slag from blast furnaces were being added to cement. ... basin, using a blend of Portland cement and locally produced metakaolin. property improvement of portland cement by ... - TRID Database https://trid.trb.org/view.aspx?id=744309 by Z Li - 2003 - Cited by 165 - Related articles This article reports on a study of Portland cement with metakaolin and slag added. ... both the compressive strength and the fluidity of the blended cement paste ...
